March 6, 2000

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Multinode Clustering:
NetWare Cluster Services Expand On Reliability
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I installed NetWare5 and Novell Cluster Services for NetWare 5 on four Gateway 7300 servers, using a Winchester Systems FlashDisk Pedestal, a RAID 5 storage device that accommodates up to four hosts via SCSI. The most difficult part of the configuration was installing NetWare on all four servers--administrators contemplating a large cluster would be well-advised to look into a software distribution mechanism, such as Novell's ZENworks for Servers.

With NetWare 5 installed on all the servers, I set up the storage subsystem. NetWare Cluster Services requires a special cluster partition on the shared storage device, so I left free space for that and created two volumes for each server on the FlashDisk. I then installed NetWare Cluster Services. The installation is straightforward and relatively simple, considering the overall complexity of the system. The only other requirement is that the administrator's workstation be running Novell's Client 32 software and the ConsoleOne management interface.

It's a good idea to read through the documentation first, as I found a couple of requirements for application installations buried relatively deep in the instructions, such as whether volumes needed to be cluster-enabled for particular applications and the requirements for cluster-enabling volumes. Cluster-enabling volumes involves creating them as a special cluster resource with their own IP address, so the files on the volume can be made available from another server (rather than just to another server) if the first server fails. The difference here is that a cluster-enabled volume is available to users after failover, while a shared volume is available only to server applications.

In general, enabling applications is a simple process. The application is installed on the primary server that will run it and may need to be installed completely on the other nodes to which it will need to failover. An application object is then created for the cluster using ConsoleOne from the administrator's console.

The object contains information about the application, such as the IP address that will be used to access the application, the scripts that will run on the server that fails and on the new server the application moves to, as well as the designated cluster nodes for the application to move to, how it should be moved (automatically or manually), and when it should move back to the original server (failback). These objects are administered through the same ConsoleOne or NWAdmin interface as any other NetWare objects--a familiar task to any NetWare administrator.

To put the cluster services through their paces, we installed several enterprise platforms: GroupWise, Novell's Distributed Print Services, Oracle8i, and Netscape's Enterprise Server.

The GroupWise cluster installation instructions recommend that GroupWise volumes not be cluster-enabled. However, other services, including file and print, would require a cluster-enabled volume, so administrators may wish to create two or more shared volumes per server, one enabled and one not.

Installing GroupWise in a clustered environment is only a little more complex than a standard installation. When GroupWise is installed on one server, the agents must be installed on the other servers, which is a step in the standard installation process. It's also recommended that you use protected memory, which is simple to enable. Once GroupWise is installed, the next step is to create a GroupWise cluster resource, also a simple task. Once the resource is created, you edit the unload and load scripts, entering the proper IP addresses for the server that should be taking over for each post office, for instance.

Installing Novell Distributed Print Services in a clustered environment is also a little more difficult than a standard installation. Once NDPS is installed on a server, you create a cluster-enabled volume for print queue information, designate that volume for NDPS queues, enable the volume in the cluster, then create an NDPS print broker and print manager. The only step that's unique to clustering is creating the cluster-enabled volume. Finally, you create the NDPS volume load and unload scripts, which designates to which server the service fails over, which servers can mount the volume, and so forth. This is a simple process involving editing the template files provided.

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